Mobile phones have various kinds of functions, and some of them have a so-called call answering function that allows a caller to leave a message when a call cannot be answered (see Patent Literatures 1 through 3).
Patent Literature 1 discloses a telephone device that, in an answering machine mode, issues an instruction to notify the terminal on the other end of a call from the terminal on the other end, and writes selected data into a received call storage unit when receiving the data selected by the terminal on the other end. In a normal mode, the telephone device instructs a display unit to display an answering message from the terminal on the other end when receiving a notification that the terminal on the other end is in an answering machine mode, and, issues an instruction to send an answering message selected based on the display on the display unit, to the terminal on the other end.
Patent Literature 2 discloses a call answering method including: the step of storing, into a storage medium, answering messages in voices of celebrities whose voices are valued; and the step of generating billing information for each voice selected from the voices.
As for a call answering service function, a system is disclosed in Patent Literature 3, which is a patent application filed by the applicant. In the answering and guiding system for unanswered calls disclosed in Patent Literature 3, when the mobile phone on the receiving end cannot answer a call, the mobile phone on the receiving end automatically identifies the caller to be notified of the unavailability on the receiving end, in accordance with conditions for notification. A notifying means notifies the caller of the reason for the unavailability and the period of time during which calls cannot be answered, and a response program attaching means sends a response program. Accordingly, in the answering and guiding system for unanswered calls, the mobile phone on the transmitting end can analyze the contents of the notification about the unavailability, activate the sent response program, and easily send a request for a reply to the receiving end through a responding unit. Meanwhile, the receiving end can analyze, through a responding unit, the response information containing the contents of the response from the transmitting end, and can automatically respond to the response information by an appropriate method.